1. Field of the Invention
The present invention relates to a plate-shaped leakage structure as an insert in a magnetic core of an inductive component, to a magnetic core having a plate-shaped leakage structure, and to an inductive component. The present invention particularly relates to chokes and transformers with a plate-shaped leakage structure inserted into same, for a facilitated adaptation of leakage path guidances, and for obtaining high, adjustable leakage inductance values.
2. Description of the Related Art
Inductive components are configured as chokes and transformers having magnetic cores. In general, a magnetic core of an inductive component is made of a ferromagnetic material, e.g. iron powder or ferrite, and serves to guide the magnetic field, while the magnetic coupling between the windings, and turns of individual windings, is improved at the same time. The winding is, in this case, formed of a conductive material, e.g. copper or aluminum, and has the shape of a flat wire, a round wire, a braided wire or a film wire.
A smoothing choke represents a specific example for an inductive component, which is used for the reduction of the residual ripple of a direct current with a superimposed ripple current. Smoothing chokes are used, for example, for voltage converters, or generally for components in which current fluctuations are not desired.
However, in various cases of application a limitation of the magnetic coupling in inductive components is only desirable to a limited extent. In transformers, for example, a certain degree of leakage inductance as current limitation in the event of a short circuit is generally desirable. For example, differential-mode interferences in current-compensated chokes are suppressed by predetermined leakage inductances. In current doubler circuits, for example, smoothing chokes are configured as coupled inductors with leakage path. It is hence common practice in many cases to adopt measures, when designing an inductive component, which reduce the magnetic coupling and increase the leakage inductance.
A simple option for increasing the leakage inductance is the reduction of the magnetic coupling between the windings by spacing the windings apart, and by interleaving them to a smallest possible extent. However, this measure helps to obtain only a very small and limited increase of the leakage inductance. To further increase the leakage inductance, moreover, discrete leakage paths of a material having a magnetic permeability <1 are introduced into a magnetic core between the windings. In many cases, air gaps are incorporated in the leakage path so as to prevent an excessive magnetic flow through the leakage path, so that the leakage inductance is effectively limited. In known E-core configurations the main and leakage inductances are adjusted, for example, by providing a winding around the outer legs, and by providing air gaps in the center leg and/or the outer legs. These known magnetic cores have the drawback, however, that they have poor mechanical properties due to the air gaps formed in the magnetic core, and are easily damaged when subjected to mechanical loads. Moreover, for adjusting the desired leakage inductance values, frequently large dimensions have to be chosen for corresponding magnetic cores, so that correspondingly produced inductive components are still in need for a very large installation space.
In other known inductive components, conventionally, leakage elements are arranged as separate core segments between the center leg and outer leg(s), wherein leakage inductances are determined by the air gaps formed between center legs, outer legs and leakage segments. In this case it has shown, however, that air gaps only have a poor homogeneous adjusting capacity, and correspondingly manufactured components go into saturation very early, with the leakage inductance slowly decreasing. This is not acceptable for a great number of applications. Due to the tolerances in the air gap, which are unavoidable in these magnetic cores, a series production is only difficult to control.
Proceeding from the conventional magnetic cores and inductive components as described above there is, therefore, a demand for a magnetic core and an inductive component in which the leakage inductance can be adjusted very accurately and reproducibly. At the same time, corresponding magnetic cores are suitable for series production.